lets see...
do not talk back, answer only when asked.
"sir" "ma'am" for everything - "yes sir" "thank you ma'am" if you speaking to anyone who isn't another recruit.
learn to love running, a lot, buy good running shoes.
arbitrary and random PT is not a form of punishment, though it may seem that way, it is a way the instructors/teachers make you able to pass the tests without issues.
the material is not hard, the books are not difficult, they all just require a lot of time and effort to make sure you pass every test.
speaking of time and studying, while in the academy consider yourself a hobbit, no friends, no life, nothing other than the academy.
Do not go out on friday nights, do not go out on dates, do not go out at all. The chance of something happening that could get you kicked out (be it a traffic citation or even a stop in some cases to being at a place where a fight occurs and you have to be a witness - good luck explaining how it wasn't your fault to your supervisor).
Staying in will allow you time to study, train and focus on the things that really matter in life, like this career, saving money and staying of trouble.
If you are single, the academy is not a time to find your spouse. Stay away from other cadets/recruits of the opposite gender (or same gender? we don't judge) in this context, you will have plenty of time to figure out that dating other officers is not the right move.
If you are dating, this is the time you sit down with your boy/girl friend and tell them you are not going to be going out because this is a very important period in your life that requires your undivided attention and that literally anything can get you kicked out of the academy. They should be understanding and keep you stress free, they need to come over to your place and have stay-in dates. This is very important, stress will manifest into mistakes at the academy and the instructors do not care about your personal life.
If you are married tell your wife/husband and kids that this is very important and that you need them to give you the room and time you need to study, train and rest.
Every single day is / should be very tiring and you will want to go to sleep early.
Always be early for roll call, if its a 7am start time, be there at 630am. This makes you get up earlier, go to sleep earlier, make sure you have enough to shower and shave, eat in the morning and get a good parking spot. Have a check list of stuff you need to bring with you everyday and do not forget anything because it may mean you get the unwanted attention of the instructors.
Never be at the back of the pack and unless you want to be in the spot light, do not be in the front. If you excel at something like running or understanding law/policy, awesome, keep your mouth shut and only offer help if someone asks for it or the instructor tells you to help. You do not want unwanted attention from anyone, it is best to be in the middle of the pack and keep to yourself.
You will make friends and enemies, this is a fact of life and the human existence. Accept it and move on. Do not show all your cards and understand that any one of you can be kicked out any at any moment.
Learn to love sleep. This is the only time in your career you will ever have day shift and weekends off unless you eventually make a high enough rank or get a special unit position. Enjoy it. Sleep in on the weekends, do not shave on the weekends, relax and unwind, you will need it.
Stay away from alcohol.
Stay away from questionable activities (protests, fundraisers/political stuff).
Stay out of bad areas.
Some of the classes are boring and some of the instructors will be very dry and lacking knowledge of the subject matter. Accept it and move on, do not say a word just do your own thing and once you are done the academy and on your FTO you can go back and say they sucked, but not before.
Learn to love coffee.
Follow the rules / policy. If the rules say you have to have a certain item on you at all times, that means you better not be caught without it. If the rules / policy say you have to do a certain thing you better do it.
Do not sleep in class, stay awake.
Do not expect special attention or special anything. You are literally just a number to the instructors and they will treat you like one if you give them a reason to.
Did I mention running? Start doing that now.
Learn how to stretch properly - injuries are a deal breaker and will make you get kicked out or held for another class, both are bad things.
If an injury happens that you cannot walk off (broken bones, twisted ankle, head trauma, etc) report it to your supervisor, they will explain the process to you.
Accept that you are not perfect, you will make mistakes and so on, use this time as a learning opportunity.
Time in the academy is like being at the gym, for months on end. This is the time you quit smoking. This is the time you start eating right, and stopping the junkfood. No chocolate, no sugar, protein packed food preferable.
Learn to love black coffee, no additions in it - yes I said this twice it is important.